Some time around 10.30pm I was sitting over dinner at a friend's place on the Upper West Side. I got a new phone yesterday, and was (rudely) fooling around with it under the table. That was when I saw a tweet saying that Osama bin Laden was dead. When I told my friends, they assumed I was joking. We switched on the TV and waited for a while as broadcast news failed to tell us anything and Twitter seethed with rumours. A mansion. A drone attack. Afghanistan, Pakistan. After President Obama's speech confirmed the news, we got in a cab and headed down to Ground Zero.

I remember being there in October 2001, standing on a corner late at night, watching the jagged shards of the World Trade Center towers being dismantled under giant spotlights. I remember being there again on the anniversary of 9/11 in 2008, watching a physical fight breaking out between flag-waving mourners and placard-carrying 9/11 "truthers".

The fear of 2001 and the ugliness of 2008 were replaced tonight by an atmosphere that veered between celebration and frank relief. The crowd was mostly of college age, young enough to have grown up with the myth of Osama bin Laden. Many of them had tumbled out of downtown bars. There were a lot of black and brown faces. They waved flags and chanted "USA! USA!". They made victory signs and blew horns and sung patriotic songs. There was, surprisingly, little of the raw aggression I was expecting. More than anything it was reminiscent of the atmosphere on Obama's election night – perhaps crossed with spring break. Obama was clearly the big winner tonight. Hastily drawn signs read "Thank you Obama" and "Obama 1, Osama 0."

Three boys climbed a lamppost and sprayed champagne on the crowd, who cheered wildly. A few people bowed their heads or held candles, perhaps more emotionally affected by the occasion than the majority, who were just there for a party, or to capture cellphone pictures for their blogs. As I left, more people were pouring in, more news reporters were setting up to do pieces to camera, and a few smiling cops were arriving, presumably to get the guys down off the lamppost.

This night seems to mark a fleeting return to the atmosphere of 2008, the "hope" and "change" that brought Obama to power. The young crowd at Ground Zero clearly hopes that the decade of fear inaugurated by 9/11 has come to an end. Whether that hope is justified remains to be seen.